L.L. Bean is hoping customers waiting for its signature product don’t get cold feet.

The company has manufactured its trademark L.L. Bean Boot and sold it to people across the United States and around the world for more than a century, but this holiday season customers who want to purchase the classic rubber-bottom boots with leather uppers may have to wait awhile to get a pair.

Company spokeswoman Carolyn Beem said Wednesday night that the Freeport-based outdoor sporting goods retailer has been unable to keep up with demand for the boots, citing their increasing popularity among high school and college students.

Beem said a large number of Bean Boot styles and sizes – the company sells 65 versions ranging in price from $79 for a low-cut moc to $199 for a shearling-lined women’s boot – are out of stock and on back order. Boots that are now being ordered online or by telephone through the retailer’s catalogs likely won’t be shipped until long after the holidays are over.

Beem said the company regrets the inconvenience and hopes customers won’t cancel their orders. She said L.L. Bean will add a third shift at its Brunswick and Lewiston manufacturing plants this week in an effort to increase production and meet the demand.

L.L. Bean also has invested more than $1 million in a new molding machine that makes the boot’s rubber bottoms. The machine is under construction in Italy and will allow the company to keep pace with future orders. The rubber bottoms are manufactured in Lewiston. The leather uppers are cut and stitched in Brunswick.

Beem said the company is currently processing about 60,000 orders for the boots, with up to 40,000 more orders expected by the end of the year. The anticipated shipping date for those boots is late February.

“We are ramping up production and working as hard as we can to fill the orders for Bean Boots,” Beem said. “These boots have been functional and fashionable since 1912. We are thrilled with the popularity of the boot.”

Not only are the boots functional – several styles are insulated with materials such as Thinsulate, shearling and lined with waterproof Gore-Tex – but they look good on your feet, especially in cold, wet climates like Maine’s, Beem said.

Beem said demand for the popular all-season boot was greater than anticipated, a trend driven by their popularity among students. Beem said the company started to notice an uptick in orders this fall, but took a cautious approach, waiting to make sure that the trend would continue before it hired more employees and added equipment.

“Everything your father or grandfather had in their closet is cool now,” Beem said, referring to the young adults who have rediscovered the boot.

Beem said the boot’s popularity got a publicity boost when the godfather of women’s footwear, Manolo Blahnik, took note of the boots last winter in New York City. He was quoted in a fashion blog as saying, “Tell someone to go and get me one pair of L.L. Beans, because I can not walk in the street.”

Scott Hood, who works at Bowdoin College in Brunswick, had been struggling to find a Christmas present for his 24-year-old son, who lives in Portland and does a lot of walking.

“When I called him and said what do you want for Christmas, he said he had no idea,” Hood recalled. “He texted me back a while later and said ‘I could use a pair of Bean Boots.’ ”

Hood proceeded to place an online order Monday night for a pair of dark brown, 10-inch boots. He had planned to give them to his son as a Christmas gift, but after learning that the boots won’t be available until Feb. 24, Hood said he might cancel his order.

According to a company history posted on L.L. Bean’s website, company founder Leon Leonwood (known as L.L.) Bean in 1912 mailed fliers to hunting license holders urging them to buy his newly created Maine Hunting Shoe. He also guaranteed the boots could be returned if the customer was not satisfied – a pledge the company still honors 102 years later.

Beem said boot stocks at retail stores – L.L. Bean operates 22 stores outside Maine – are kept separate from the boots that are ordered online. She suggested customers who can’t wait for their boots to be shipped should check their local store for availability.

The company’s flagship store on Main Street in Freeport has some Bean Boots in stock, according to Corey Bouyea, the retail operations manager.

“We hope that our customers will understand that we are doing everything possible to provide them with a great product,” Beem said. “We hope they agree that they are worth the wait.”